Generally, the hard disk drive (HDD) includes the suspension substrate on which a magnetic head slider mounted. In this case, the magnetic head slider is provided for writing and reading data relative to a disk adapted for storing therein the data. The suspension substrate includes a metallic support layer and a wiring layer having a plurality of wirings layered on the metallic support layer, via an insulating layer. With this configuration, by flowing or sending an electric signal through each wiring, the writing and reading of the data relative to the disk can be performed.
In the hard disk drive of this type, an actuator arm for supporting the magnetic head slider and a VCM actuator (e.g., a voice coil motor) are provided respectively. In this case, in order to move the magnetic head slider to a desired data track on the disk, the actuator arm is pivoted by the VCM actuator, under control of a servo-control system.
In recent years, for an attempt to provide a more high-density disk, the width of each data track has been narrowed. However, in some cases, such an attempt makes it rather difficult to accurately align the magnetic head slider with the desired track, by using the VCM actuator.
To address this problem, the suspension of the so-called dual actuator type has been reported. In this case, the VCM actuator is cooperated with a PZT micro-actuator (or DSA (Dual Stage Actuator)), in order to move the magnetic head slider to the desired track (e.g., see 3P2010-86649A). Specifically, the PZT micro-actuator is composed of a piezoelectric element composed of lead titanate zirconate (PZT) and configured to be expanded and contracted with application of a voltage, thus enabling the magnetic head slider to be finely moved. Namely, in the suspension of the dual actuator type, the VCM actuator serves to roughly control the position of the magnetic head slider, while the PZT micro-actuator serves to finely control the position of the magnetic head slider. In this way, the magnetic head slider can be aligned, rapidly and accurately, with the desired track.
For instance, in the suspension substrate disclosed in the above JP2010-86649A, a through hole for exposing a wiring section is provided in an electric insulating layer, in a terminal portion for supplying electricity to the piezoelectric element, and a ring-like liquid stopper is provided in the piezoelectric element's side of the electric insulating layer. With this configuration, by injecting a liquid conductive adhesive into the liquid stopper, the piezoelectric element can be joined to the terminal portion, as well as the electrode of the piezoelectric element located on the side of the suspension substrate can be electrically connected with the wiring section. Meanwhile, the electrode of the piezoelectric element located on the side opposite to the suspension substrate is electrically connected with a base plate.